1. Field of the Invention
The present invention relates to a vibrating gyroscope and an electronic device using the same, and more specifically, it relates to a vibrating gyroscope for use in video cameras having an anti-camera-shake function, car navigating systems, pointing devices, and the like, and an electronic device using the same.
2. Description of the Related Art
FIG. 11 is a perspective view of a vibrating gyroscope comprising a vibrator 50, and FIGS. 12A-12C show a plan view, a front view, and a bottom view, respectively, thereof. The vibrating gyroscope shown in FIGS. 11 and 12A-12C is disclosed in Japanese Unexamined Patent Application Publication No. 11-125526.
In FIG. 11, the vibrator 50 includes a first piezoelectric substrate 101 having one principal plane on which a first strip electrode is formed on the top surface and which is polarized in the thickness direction; and a second piezoelectric substrate 102 having one principal plane on which a second strip electrode is formed on its bottom surface and which is polarized in the thickness direction. The other principal plane of the first piezoelectric substrate 101 and the other principal plane of the second piezoelectric substrate 102 are bonded via an intermediate electrode 103.
The first strip electrode has a dividing slot S0 extending in the longitudinal direction thereof, and dividing slots S1 and S2 that are formed widthwise of the first strip electrode to be slightly closer in the longitudinal direction to the center than the positions to which nodes N1 and N2 are vertically projected on the first strip electrode. Hence, the first strip electrode is divided into electrode parts 104 and 105 by the dividing slot S0, and the electrode parts 104 and 105 are further divided into the electrode parts 104a, 104b, 104c, 105a, 105b, and 105c by the dividing slots S1 and S2. The second strip electrode is composed of an electrode part 106a. 
Supporting members 107a and 107b which also function as leads are disposed at positions to which the nodes N1 and N2 of the vibrator 50 are projected on the first strip electrode; and supporting members 507c and 507d which also function as leads are disposed at positions to which the nodes N1 and N2 are projected on the second strip electrode. A technique such as soldering is used to connect the supporting member 107a to the electrode parts 105a, 104b, and 105b; the supporting member 107b to the electrode parts 104a, 104c, and 105c; and the supporting members 507c and 105d to the electrode part 106a. The supporting members 107a, 107b, 507c, and 507d are made of the same material, are configured in the same form, and have the same rigidity.
By fixing the ends of the supporting members 107a, 107b, 507c, and 507d, and by applying drive signals to the electrode part 106a serving as a drive electrode via the supporting members 507c and 507d, the vibrator 50 having such a structure undergoes flexural vibration in the thickness direction with free longitudinal ends, where the nodes for the lowest order mode are the nodes N1 and N2. Since the first piezoelectric substrate 101 and the second piezoelectric substrate 102 are held by the supporting members 107a, 107b, 507c, and 507dhaving the same rigidity, the nodes N1 and N2 are formed substantially at the middle between the first strip electrode and the second strip electrode in the thickness direction.
The conventional vibrating gyroscopes have a problem in that there exists a deviation in the vibrating characteristic of the vibrator between respective vibrating gyroscopes produced by the same production method. In addition, the vibrating characteristic of each vibrating gyroscope shifts differently in response to the change in the ambient temperature and over time.
It is therefore an object of the present invention to reduce the deviation in the vibrating characteristic of the vibrator between respective vibrating gyroscopes and realize a vibrating gyroscope which can detect an angular velocity precisely.
The foregoing and other objects are achieved in accordance with certain features of the invention by a vibrating gyroscope which comprises a vibrator having a longitudinal direction and being capable of vibrating in a bending mode in a bending direction perpendicular to the longitudinal direction. The vibrator has first and second nodes which elongate in a direction perpendicular to both the bending direction and the longitudinal direction and first, second, third and fourth supporting member connected to the vibrator such that the first node is interposed between the first and second supporting members and the second node is interposed between the third and fourth supporting members. The first node is located at the vicinity of either the first supporting member or the second supporting member, and the second supporting member is located at the vicinity of either third supporting member or the fourth supporting member.
It is preferable that the first supporting member and the second supporting member have the different rigidities, and the third supporting member and fourth supporting member have the different rigidities. To this end, the first supporting member and the second supporting member may have different shapes from each other or have different cross sections from each other. The first supporting member and the second supporting member may also be made of different materials.
According to a vibrator of the present invention, supporting members having different rigidities are located at positions to which nodes are projected on a first strip electrode and a second strip electrode. Hence, the nodes are displaced toward either the first strip electrode or the second strip electrode with respect to the thickness direction. Therefore, there is less variation in the nodes of the vibrator with respect to the thickness direction, and there is less variation in the driving balance of the vibrator, thus providing an accurate determination of angular velocity.
A vibrating gyroscope according to the present invention is less affected by disturbances or changes over time because the driving balance of a vibrator is maintained for stable vibration, thus providing an accurate determination of angular velocity.
An electronic device according to the present invention incorporates a vibrating gyroscope capable of accurately determining an angular velocity, thus forming a precise control mechanism.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.